The crowd had gathered to watch country musician Jason Aldean perform, part of a three-day festival. It is the deadliest shooting in American history, to date.

The shooter, 64-year-old Stephen Paddock from Mesquite, Nevada was found dead in his hotel room.

People reports that 23 weapons were discovered in his hotel room, most of which were military-style rifles. At least one of those rifles had been modified with a“bump stock” style device, which allows for rapid fire without a technical conversion to a fully automatic gun. That device alters the gun’s stock so that the shooter can pull the trigger faster. Other weapons found in Paddock’s possession were converted to fully automatic. Four Daniel Defense DDM4 rifles, three FN-15s and other rifles made by Sig Sauer were found. According to the Los Angeles Times, they were purchased legally.

Police said that at least 10 suitcases were used to transport the weapons to Paddock’s Mandalay Bay’s hotel room.

An additional 19 weapons were found at the shooter’s home, according to PEOPLE. In addition to the guns, explosives and several thousand rounds of ammunition were found. Material used to make explosives were also located in his car.

Police reveal that Paddock used a "hammer-like device" to smash out his hotel window before shooting through it.

As for a motive, police aren’t disclosing any details if they have them.

“I can’t get into the mind of a psychopath at this point,” Clark County Sheriff Joseph Lombardo said at a news conference Monday.

Paddock's brother Eric said Stephen was multimillionaire, according to the Associated Press. He worked as an accountant and made money through real estate. He described his sibling as "not a normal guy" who "played high stakes video poker." He also reportedly owned two planes.

"He's just a guy who played video poker and took cruises and ate burritos at Taco Bell. There's no political affiliation that we know of. There's no religious affiliation that we know of," Eric said, according to The Washington Post.

Some of Stephen's neighbors described Paddock as "extremely standoffish" and "aggressively unfriendly," Fox News reports.